Based on our previous studies it is extremely important to continue to study temporal variations in plaque during caries formation. Plaque samples will be examined microbiologically and immunologically and S. mutans strains will be quantitated by the new immunofluorescent technique. New strains of cariogenic organisms will be isolated and checked for caries activity in animals, and their biochemical and microbiological characteristics will be determined. Studies on the metabolic activities of S. mutans will be continued to determine methods by which they may be inhibited. The information so obtained may ultimately be applied to the determination of the characteristics of high caries-risk individuals, those who would benefit most by treatment.